HarmonyOS 将订阅下载任务进度事件实现同步效果

可以参考链接：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-taskpool-V5#adddependency11

示例代码：

@Concurrent
function delay(args: number): number {
  let t: number = Date.now();
  while ((Date.now() - t) < 1000) {
    continue;
  }
  return args;
}

let task1: taskpool.Task = new taskpool.Task(delay, 100);
let task2: taskpool.Task = new taskpool.Task(delay, 200);
let task3: taskpool.Task = new taskpool.Task(delay, 200);

console.info("dependency: add dependency start");
task1.addDependency(task2);
task2.addDependency(task3);
console.info("dependency: add dependency end");

console.info("dependency: start execute second")
taskpool.execute(task1).then(() => {
  console.info("dependency: second task1 success");
})
taskpool.execute(task2).then(() => {
  console.info("dependency: second task2 success");
})
taskpool.execute(task3).then(() => {
  console.info("dependency: second task3 success");
})